Methods Of Forming Metal-Containing Structures, And Methods Of Forming Germanium-Containing Structures

ABSTRACT

Some embodiments include methods of forming metal-containing structures. A first metal-containing material may be formed over a substrate. After the first metal-containing material is formed, and while the substrate is within a reaction chamber, hydrogen-containing reactant may be used to form a hydrogen-containing layer over the first metal-containing material. The hydrogen-containing reactant may be, for example, formic acid and/or formaldehyde. Any unreacted hydrogen-containing reactant may be purged from within the reaction chamber, and then metal-containing precursor may be flowed into the reaction chamber. The hydrogen-containing layer may be used during conversion of the metal-containing precursor into a second metal-containing material that forms directly against the first metal-containing material. Some embodiments include methods of forming germanium-containing structures, such as, for example, methods of forming phase change materials containing germanium, antimony and tellurium.

TECHNICAL FIELD

Methods of forming metal-containing structures, and methods of forminggermanium-containing structures.

BACKGROUND

Integrated circuit (IC) fabrication often involves formation ofmetal-containing materials over semiconductor substrates. Such formationmay utilize a deposition process such as, for example, one or more ofatomic layer deposition (ALD), chemical vapor deposition (CVD) andphysical vapor deposition (PVD).

A metal-containing material is any material that comprises “metal.” Theelements of the periodic table may be classified as being either metalsor nonmetals on the basis of their general physical and chemicalproperties. However, a few elements have intermediate properties, andthese elements are sometimes classified as metalloids. The metalloidsinclude boron, silicon, germanium, arsenic, antimony, tellurium andpolonium. The term “metal” is utilized herein and in the claims thatfollow to refer to any element that would not be classified as a“nonmetal”, and thus includes metalloids as well as regular metals.

The metal-containing materials incorporated into ICs may be utilized inany of numerous devices and structures. For instance, themetal-containing materials may be utilized for electrically conductivestructures (for instance, conductive regions of wordlines, bitlines, andother lines; electrodes of capacitors; bond pads; etc.), and/or forphase change materials (for instance, mixtures of germanium, antimonyand tellurium may be utilized to form phase change materials).

The properties of metal-containing materials may be altered by thepurity of the metal-containing materials, and often desired electricalproperties are better achieved with high purity metal-containingmaterials than with lower purity metal-containing materials. Also, itcan be easier to maintain consistency amongst a plurality of devices ifthe metal-containing materials are of high purity than if themetal-containing materials are of lower purity, since the types andamounts of impurities within the lower purity metal-containing materialsmay fluctuate—which may lead to differences in electrical propertiesamongst the devices.

One method of forming metals is to utilize metal amidinates and ammoniain ALD processes. For instance, germanium may be deposited utilizingsequential pulses of germanium amidinate [such as, for example, bis(N,N′-diisopropyl-butylamidinate)-N-germanium (II)], and ammonia.however, the layers formed by such deposition may contain high levels ofcarbon and nitrogen contamination; with example high levels of carbonand nitrogen contamination being about eight atomic percent and aboutfive atomic percent, respectively.

Another method of forming metals to utilize formic acid to reduce metalamidinates during CVD processes. For instance, copper amidinate may bereduced by formic acid during a CVD process to form a copper deposit. Itis believed that the copper acts as a catalyst during the CVD process toform monatomic hydrogen from the catalytic decomposition of formic acid,and that such hydrogen then reduces the amidinate to form the copperdeposit.

Although the formic acid CVD processes work with some metal amidinates,there are other metal amidinates that lack the ability to self-catalyzeformation of hydrogen from formic acid, and that accordingly are notsuitable for utilization in the formic acid CVD processes.

It is desired to develop new methods of forming metal-containingmaterials suitable for utilization in integrated circuitry.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart diagram of an embodiment.

FIGS. 2-7 are a diagrammatic, cross-sectional side views of a portion ofa semiconductor construction shown at various process stages of anembodiment.

FIGS. 8 and 9 are diagrammatic, cross-sectional side views of a portionof a semiconductor construction shown at various process stages of anembodiment.

FIG. 10 is a diagrammatic, cross-sectional side view of a portion of asemiconductor construction shown at a process stage of an embodiment.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

In some embodiments, ALD methods are utilized for formingmetal-containing materials from metal-containing precursors (such as,for example, metal amidinate precursors). The ALD methods utilize one orboth of formic acid and formaldehyde in addition to the metal-containingprecursors.

Prior to utilization of the ALD, a metal-containing surface is formedacross a semiconductor substrate. The metal-containing surface may beformed with any suitable processing.

In operation, the metal-containing surface is used as a catalyst to formhydrogen from formic acid (and/or formaldehyde) in a first ALD stage.Subsequently, the hydrogen is used to break down a metal-containingprecursor in a second ALD stage. This is in contrast to the prior artmethods of formic acid CVD (discussed above in the “background” section)in which the metal of a metal amidinate is simultaneously utilized asboth a catalyst for breaking down formic acid, and as a depositedmaterial resulting from reduction of the metal amidinate.

An example embodiment is described with reference to a flow chart ofFIG. 1. An initial processing stage 2 comprises provision of a substrateinto a reaction chamber. The substrate may be, for example, asemiconductor substrate, such as a monocrystalline silicon wafer at aprocessing stage associated with the fabrication of integratedcircuitry. The substrate has a metal-containing surface. Themetal-containing surface may be formed with any suitable processing. Insome embodiments, the metal-containing surface may be formed bydeposition of metal-containing material utilizing one or more of ALD,CVD and PVD. Such metal-containing material may comprise, consistessentially of, or consist of, for example, tungsten, titanium, copper,aluminum, ruthenium, germanium, antimony, tellurium, etc.

While the substrate is within the reaction chamber, processing stage 4of the flow chart of FIG. 1 is conducted. Specifically, themetal-containing surface is exposed to a hydrogen-containing reactant toform a hydrogen-containing layer. The hydrogen-containing reactant maycomprise, consist essentially of, or consist of one or both of formicacid and formaldehyde.

At processing stage 6 of the flow chart of FIG. 1, any unreactedhydrogen-containing reactant is removed from within the chamber with asuitable purge. Such purge may utilize, for example, flow of an inertpurging gas through the chamber, and/or vacuum to draw any unreactedhydrogen-containing reactant out of the chamber.

At processing stage 8 of the flow chart of FIG. 1, metal-containingprecursor is flowed into the reaction chamber, and thus thehydrogen-containing layer is exposed to the metal-containing precursor.The metal-containing precursor may comprise a metal amidinate, such as,for example, germanium amidinate. The exposure of the metal-containingprecursor to the hydrogen-containing layer may reduce the amidinate, andthereby release metal from the metal-containing precursor to form afresh metal-containing surface over the initial metal-containing surfacethat had been present at the processing stage 2 of FIG. 1.

In some embodiments, the metal released from the metal-containingprecursor is the same as the metal of the initial metal-containingsurface at the processing stage 2 of FIG. 1. Thus the processing of FIG.1 may be utilized to create several layers of the same metal. The layersmay be considered to merge into a single thick structure comprising,consisting essentially of, or consisting of the metal. In otherembodiments, the metal released from the metal-containing precursor isdifferent from the initial metal-containing surface at the processingstage 2 of FIG. 1. Thus, the processing of FIG. 1 may be utilized tocreate multiple layers of different metals.

At processing stage 10 of the flow chart of FIG. 1, any unreactedmetal-containing precursor is removed from within the chamber with asuitable purge.

A dashed line 12 is provided to show that the processing stages 4, 6, 8and 10 may be repeated in multiple iterations to form a stack of layers.The fresh metal-containing surface formed at processing stage 8 will bethe metal-containing surface utilized at the processing stage 4 duringiterations that have processing stage 4 following processing stage 10.The metal-containing precursor may be varied in embodiments thatutilized multiple iterations of processing stages 4, 6, 8 and 10; or maybe the same during the multiple iterations.

FIGS. 2-10 show semiconductor constructions at processing stages of someexample embodiments.

Referring to FIG. 2, a portion of a semiconductor construction 20 isillustrated. The semiconductor construction comprises a semiconductorsubstrate 22 having a metal-containing material 24 formed thereover. Themetal-containing material 24 has an upper metal-containing surface 25.

Semiconductor substrate 22 may, for example, comprise, consistessentially of, or consist of monocrystalline silicon lightly doped withbackground p-type dopant. The terms “semiconductive substrate,”“semiconductor construction” and “semiconductor substrate” mean anyconstruction comprising semiconductive material, including, but notlimited to, bulk semiconductive materials such as a semiconductive wafer(either alone or in assemblies comprising other materials thereon), andsemiconductive material layers (either alone or in assemblies comprisingother materials). The term “substrate” means any supporting structure,including, but not limited to, the semiconductive substrates describedabove. Although the substrate 22 is shown to be homogeneous, in someembodiments the substrate may comprise one or more layers or structuresassociated with integrated circuit fabrication. Such layers orstructures may be electrically insulative, electrically conductive,and/or semiconductive.

Metal-containing material 24 may comprise any metal-containing material,and may be in any suitable configuration. Accordingly, althoughmetal-containing material 24 is shown as a layer extending across anupper planar surface of substrate 22, in other embodiments the metallayer may extend across an undulating topography; and may, for example,extend into a trench or over a pillar.

In some embodiments, metal-containing material 24 may comprise, consistessentially of, or consist of, for example, tungsten, titanium, copper,aluminum, ruthenium, germanium, antimony, tellurium, etc.

The metal-containing material 24 may be formed by any suitableprocessing, and in some embodiments may be deposited by one or more ofALD, CVD and PVD. The metal-containing material 24 may be referred to asa first metal-containing material to distinguish it from othermetal-containing materials formed in subsequent processing (discussedbelow).

The semiconductor construction of FIG. 2 may be considered to be thesubstrate described at the processing stage 2 of the flow chart of FIG.1, and accordingly may be provided within an ALD reaction chamber (notshown).

Referring to FIG. 3, hydrogen-containing reactant 26 is utilized to forma hydrogen-containing layer 28 across the surface 25 of metal-containingmaterial 24. The hydrogen-containing reactant 26 may comprise, consistessentially of, or consist of one or both of formic acid andformaldehyde; and the hydrogen-containing layer 28 may comprise, consistessentially of, or consist of monatomic hydrogen created by catalyticdecomposition of hydrogen-containing reactant 26 using metal ofmetal-containing layer 24. The hydrogen-containing reactant 26 may bealternatively referred to as a hydrogen-containing material, or as ahydrogen-containing precursor.

The processing stage of FIG. 3 may be considered to be an ALD processingstage, and accordingly hydrogen-containing layer 28 may be a monolayer,or partial monolayer, created through ALD processing. Construction 20 iswithin the ALD reaction chamber described with reference to FIG. 1during the exposure of metal-containing layer 24 to hydrogen-containingreactant 26. The hydrogen-containing reactant 26 may be flowed into theALD reaction chamber and left in the chamber under suitable temperatureand pressure, and for a suitable duration, to form hydrogen-containinglayer 28 as a saturated monolayer across the surface 25 ofmetal-containing material 24.

The semiconductor construction of FIG. 3 may be considered to be at theprocessing stage 4 of the flow chart of FIG. 1.

Referring to FIG. 4, any unreacted hydrogen-containing reactant 26 (FIG.3) is removed from the ALD reaction chamber to leave the illustratedstructure having hydrogen-containing layer 28 over metal-containingsurface 25. The hydrogen-containing reactant may be removed with anysuitable purge.

The semiconductor construction of FIG. 4 may be considered to be at theprocessing stage 6 of the flow chart of FIG. 1.

Referring to FIG. 5, metal-containing precursor 30 is utilized to form asecond metal-containing material 32 directly against the firstmetal-containing material 24 (the term “directly against” is used toindicate that there are no intervening materials between the first andsecond metal-containing materials). The metal-containing precursor 30may be flowed into the ALD reaction chamber after thehydrogen-containing material 26 (FIG. 3) has been exhausted from thechamber. The metal-containing precursor interacts with thehydrogen-containing layer 28 (FIG. 4) to convert the precursor into themetal of the second metal-containing layer 32. In some embodiments, themetal-containing precursor 30 may comprise a metal amidinate, and mayinteract with the hydrogen-containing layer 28 (FIG. 4) to causereduction of the amidinate through the reaction of hydrogen of thehydrogen-containing layer with the amidinate. The hydrogen of thehydrogen-containing layer is incorporated into a reaction by-productwhile metal is released from the amidinate. Thus, the net reactionresults in replacement of hydrogen-containing layer 28 (FIG. 4) with thesecond metal-containing material 32.

The second metal-containing material 32 may comprise any suitable metal,and in some embodiments may comprise, consist essentially of, or consistof one or more of germanium, antimony and tellurium. Accordingly, themetal-containing precursor 30 may comprise, consist essentially of, orconsist of germanium-containing precursor, antimony-containingprecursor, or tellurium-containing precursor (for instance, germaniumamidinate, antimony amidinate, or tellurium amidinate), in someembodiments.

The semiconductor construction of FIG. 5 may be considered to be at theprocessing stage 8 of the flow chart of FIG. 1.

Referring to FIG. 6, any unreacted metal-containing precursor 30 (FIG.5) is removed from the ALD reaction chamber to leave the illustratedstructure having the second metal-containing material 32 directlyagainst the metal-containing surface 25. The metal-containing precursormay be removed with any suitable purge.

The second metal-containing material 32 may contain a common metal asthe first metal-containing material 24 in some embodiments, and may beentirely of a different metal from the first metal-containing material24 in other embodiments. For instance, in some embodiments materials 24and 32 may both be predominantly germanium (and may both consistessentially of, or consist of germanium); and in other embodiments oneof the materials 24 and 32 may be predominantly germanium (and mayconsist essentially of, or consist of germanium in some embodiments)while the other of the materials 24 and 32 is predominantly antimony ortellurium (and may consist essentially of, or consist of antimony ortellurium in some embodiments).

The semiconductor construction of FIG. 6 may be considered to be at theprocessing stage 10 of the flow chart of FIG. 1.

The metal-containing material 32 may be much purer than metal-containingmaterials formed by conventional methods. For instance, ifmetal-containing material 32 comprises germanium formed utilizing formicacid as the hydrogen-containing reactant, and utilizing germaniumarnidinate as the metal-containing precursor, the material 32 may have apurity of greater than 95 atomic percent, or even greater than 99 atomicpercent, relative to carbon, nitrogen and oxygen contamination, asmeasured by x-ray photoelectron spectroscopy (XPS).

The processing of FIGS. 3-6 may be considered to represent ALDprocessing in which a monolayer of hydrogen (layer 28 of FIGS. 3 and 4)is initially formed from hydrogen-containing reactant within an ALDreaction chamber, and then utilized to form a monolayer of metal (layer32 of FIGS. 5 and 6) from metal-containing precursor within the ALDreaction chamber. The metal-containing precursor and hydrogen-containingreactant would be within the ALD reaction chamber at different andsubstantially non-overlapping times relative to one another. In otherwords, all, or least substantially all, of the hydrogen-containingreactant is removed from within the reaction chamber prior tointroduction of the metal-containing precursor; and if multipleiterations of the process are conducted, all, or at least substantiallyall of the metal-containing precursor is removed from within thereaction chamber prior to introduction of the hydrogen-containingprecursor. The term “substantially all” indicates that any amount of theindicated material remaining within the reaction chamber is too low forgas phase reactions from such material to interfere with subsequentdepositions utilizing other materials. In some embodiments, such maymean that at least all measurable amounts of the indicated material areremoved from within the reaction chamber.

Referring to FIG. 7, the processing of FIGS. 3-6 may be repeated to formanother metal-containing material 34 directly against metal-containingmaterial 32. The metal-containing material 34 may have a metal in commonwith metal-containing material 32, or may consist of a different metalfrom the metal of metal-containing material 32.

Another embodiment is described with reference to FIGS. 8 and 9. Inreferring to FIGS. 8 and 9, similar numbering will be used as is usedabove to describe FIGS. 2-7, where appropriate.

FIG. 8 shows a semiconductor construction 40 comprising a substrate 22and a material 42 formed over the substrate. Material 42 may comprisegermanium, and may be formed by any suitable method. In someembodiments, material 42 may be formed by ALD utilizing sequentialpulses of germanium amidinate and ammonia. The ALD forms a plurality oflayers which stack together to form material 42 to a desired thickness.As discussed above in the “background” section, the germanium-containinglayers formed by deposition with germanium amidinate and ammonia mayhave high levels of carbon and nitrogen contamination. However, material42 may be formed solely to provide a starting surface for subsequent ALDof the type described in FIG. 1 (i.e., ALD with formic acid orformaldehyde), which can then form a relatively high puritygermanium-containing material over material 42.

In an example embodiment, material 42 may be formed to a thickness ofless than or equal to about 25 angstroms. For instance, material 42 maybe formed with less than or equal to about 100 ALD cycles utilizinggermanium amidinate and a reductant (for instance, ammonia or H₂). TheALD process may utilize any suitable conditions, such as, for example, achuck set point temperature of from about 200° C. to about 400° C., achamber pressure of from about 10⁻⁴ Torr to about 10 Torr, with thegermanium amidinate being heated to about 85° C. and flowed into thereaction chamber with helium as a carrier gas, and with the ammoniabeing flowed into the reaction chamber at about room temperature.

Material 42 has an upper surface 43, and such surface may be referred toas an initial germanium-containing surface.

Referring to FIG. 9, a material 44 is formed over surface 43 of material42. Materials 42 and 44 may be referred to as first and secondmaterials, respectively. Material 44 may comprise, consist essentiallyof, or consist of germanium; and may be formed by an ALD processutilizing germanium amidinate and one or both of formic acid andformaldehyde with processing analogous to that described with referenceto FIGS. 1-6. In an example embodiment, material 44 is formed to be atleast about four times thicker than material 42. For instance, material44 may be formed with at least about 400 ALD cycles utilizing germaniumamidinate and formic acid. The ALD process may utilize any suitableconditions, such as, for example, a chuck set point temperature of fromabout 200° C. to about 400° C., a chamber pressure of from about 10⁻⁴Torr to about 10 Torr, with the germanium amidinate being heated toabout 85° C. and flowed into the reaction chamber with helium as acarrier gas, and with the formic acid being flowed into the reactionchamber at about room temperature.

The materials 42 and 44 together form a germanium-containing structure.The high purity of material 44, combined with the large relative amountof material 44 to material 42, enables the germanium-containingstructure to be formed with high overall purity.

The embodiments discussed above may be utilized to form numerousstructures and devices. FIG. 10 shows a portion of a semiconductorconstruction 50 illustrating one example structure, and specificallyillustrating formation of a phase change structure 52 over asemiconductor substrate 22. The phase change structure includes aplurality of materials 54, 55, 56, 57, 58 and 59. At least some of thematerials may be formed by atomic layer deposition. The individualmaterials may be of any suitable thickness, and in some embodiments maybe very thin (for instance, may be formed with less than or equal to 10ALD cycles) so that the structure 52 behaves like a mixture of thecompositions utilized for materials 54, 55, 56, 57, 58 and 59.

In some embodiments, some of the materials 54-59 will comprise antimony,others tellurium, and yet others germanium. At least the materials thatcomprise germanium may be formed with ALD utilizing germanium amidinateand one or both of formic acid and formaldehyde, with processinganalogous to one or more of the embodiments discussed above withreference to FIGS. 1-9. In some embodiments it will only be thegermanium that is formed with processing analogous to embodimentsdiscussed above with reference to FIGS. 1-9, and the other materials(specifically, the materials comprising antimony or tellurium) will beformed with conventional methods. In alternative embodiments, materialscomprising antimony and/or materials comprising tellurium may also beformed with processing utilizing methods discussed above with referenceto FIGS. 1-9.

The phase change structure 52 may have any suitable shape andcompositional configuration, and may be incorporated into integratedcircuitry devices. For instance, the phase change structure may beincorporated into memory devices of a phase change random access memory(PCRAM) array.

Although the embodiments discussed above were described with referenceto integrated circuit fabrication, several of the embodiments may beutilized for fabrication of other structures in addition to, oralternatively to, integrated circuit structures. For instance, someembodiments may be utilized for fabrication of microelectromechanicalsystems (MEMS).

In compliance with the statute, the subject matter disclosed herein hasbeen described in language more or less specific as to structural andmethodical features. It is to be understood, however, that the claimsare not limited to the specific features shown and described, since themeans herein disclosed comprise example embodiments. The claims are thusto be afforded full scope as literally worded, and to be appropriatelyinterpreted in accordance with the doctrine of equivalents.

1. A method of forming a metal-containing structure, comprising: forminga first metal-containing material over a substrate; after forming thefirst metal-containing material, and while the substrate is within areaction chamber, utilizing hydrogen-containing reactant to form ahydrogen-containing layer over the first metal-containing material;removing any unreacted hydrogen-containing reactant from within thereaction chamber; and after removing unreacted hydrogen-containingreactant from within the reaction chamber, flowing metal-containingprecursor into the reaction chamber and utilizing hydrogen of thehydrogen-containing layer during conversion of the metal-containingprecursor into a second metal-containing material, the secondmetal-containing material being directly against the firstmetal-containing material.
 2. The method of claim 1 wherein thehydrogen-containing reactant includes one or both of formic acid andformaldehyde.
 3. The method of claim 1 wherein the hydrogen-containingreactant comprises formic acid.
 4. The method of claim 1 wherein thehydrogen-containing reactant comprises formaldehyde.
 5. The method ofclaim 1 wherein the first and second metal-containing materials comprisea common metal with one another.
 6. The method of claim 5 wherein thecommon metal is germanium.
 7. The method of claim 1 wherein the firstand second metal-containing materials comprise different metals relativeto one another.
 8. The method of claim 1 wherein the firstmetal-containing material comprises antimony or tellurium, and whereinthe second metal-containing material comprises germanium.
 9. A method offorming a metal-containing structure, comprising: flowinghydrogen-containing reactant into a reaction chamber having asemiconductor substrate therein, the hydrogen-containing reactantcomprising one or both of formic acid and formaldehyde, thesemiconductor substrate having a metal-containing surface, thehydrogen-containing reactant forming a hydrogen-containing layer acrossthe metal-containing surface; flowing a metal-containing precursor intothe reaction chamber, the metal-containing precursor reacting withhydrogen from the hydrogen-containing layer to form a metal-containingmaterial directly against the metal-containing surface; and wherein themetal-containing precursor and hydrogen-containing reactant are withinthe reaction chamber at different and substantially non-overlappingtimes relative to one another.
 10. The method of claim 9 wherein thehydrogen-containing reactant comprises formic acid.
 11. The method ofclaim 9 wherein the hydrogen-containing reactant comprises formaldehyde.12. The method of claim 9 wherein the metal-containing surface comprisesgermanium, and wherein the metal-containing material also comprisesgermanium.
 13. The method of claim 9 wherein the metal-containingsurface comprises antimony or tellurium, and wherein themetal-containing material comprises germanium.
 14. The method of claim 9wherein the metal-containing material is a first metal-containingmaterial, and further comprising: flowing the hydrogen-containingreactant into the reaction chamber to form a subsequenthydrogen-containing layer over a surface of the first metal-containingmaterial; flowing a subsequent metal-containing precursor into thereaction chamber to form a subsequent metal-containing material over thefirst metal-containing material; and wherein the subsequentmetal-containing precursor and the subsequent hydrogen-containingreactant are within the reaction chamber at different and substantiallynon-overlapping times relative to one another.
 15. The method of claim14 wherein the first metal-containing material and the subsequentmetal-containing material comprise a common metal with one another. 16.The method of claim 15 wherein the common metal is germanium.
 17. Themethod of claim 14 wherein the first metal-containing material and thesubsequent metal-containing material comprise different metals relativeto one another.
 18. A method of forming germanium-containing structures,comprising: forming an initial germanium-containing surface over asemiconductor substrate; and after forming the initialgermanium-containing surface, performing at least one iteration of thefollowing sequence: flowing hydrogen-containing reactant into a reactionchamber to form a hydrogen-containing layer across thegermanium-containing surface; removing any unreacted hydrogen-containingreactant from within the reaction chamber; and after removing unreactedhydrogen-containing reactant from within the reaction chamber, flowinggermanium-containing precursor into the reaction chamber, thegermanium-containing precursor reacting with hydrogen from thehydrogen-containing layer to form germanium-containing material, thegermanium-containing material having a germanium-containing surface fora subsequent iteration.
 19. The method of claim 18 wherein the formingof the initial germanium-containing surface comprises at least oneiteration of an atomic layer deposition sequence.
 20. The method ofclaim 18 wherein the forming of the initial germanium-containing surfacecomprises at least one iteration of an atomic layer deposition sequenceutilizing germanium amidinate and reductant.
 21. The method of claim 20wherein the reductant comprises one or both of H₂ and NH₃.
 22. Themethod of claim 20 wherein the at least one iteration of the atomiclayer deposition sequence utilizing germanium amidinate and reductantforms a first germanium-containing material, and wherein the sequenceutilizing the hydrogen-containing reactant and germanium-containingprecursor forms a second germanium-containing material; and wherein thefirst germanium-containing material is less pure in germanium than thesecond germanium-containing material.